Invaluable Assets in limb salvage
Orange County, CA - June 2nd 2016 - Before considering amputation as a solution for chronic wounds, reviewing potential revascularization methods can offer the possibility of limb salvage. If amputation is an unavoidable option, revascularization presents the ability to reduce the severity of limb loss.
According to Endovascular Today, the rate of amputation related to chronic wounds is more than 50 percent at the 5 year follow-up mark, but can be reduced by 8.2 to 21.1 percent with direct revascularization. During this process, perfusion is restored to a part of the body overtaken with ischemia; a methodology that includes analysis, diagnosis, and treatment. There are two main revascularization processes—vascular bypass and angioplasty.
“A lot of our patients with vascular issues are diabetics or smokers; those conditions tend to lead to problems with vessels” said Rocco Garcia, Diagnostic Radiological Technologist and Intervention Radiology Technologist at the Long Beach Veterans Health Administration.
The common cause for chronic wounds is Atherosclerosis. As the disease develops, fatty deposits known as plaque close in on artery walls, subsequently reducing blood flow wherever the blockage occurs. This causes Peripheral Artery Disease (PAD), a precursor to critical limb ischemia (chronic wounds) or stroke and heart attack.
Garcia said there is a host of ways in which revascularization can be achieved, such as undergoing a balloon angioplasty and taking prescription medicine to dissolve plaque build-up. Regardless, diagnostic imaging is the key to limb salvage when adopting this alternative method to amputation.
These procedures are used to plan treatment based on the location and degree of blockage. The initial step includes a Doppler evaluation, which gives physicians the ability to see blood flow through a vessel or artery. A combination of different imaging modalities, such as X-Ray Fluorescence Angiography, Computed Tomography Angiography (CTA), and Magnetic Resonance Angiography are required to treat ineffective tissue perfusion.
Chison’s Sonotouch 30 Ultrasound Imaging System is an ideal unit to perform Doppler evaluations. The compact and durable LED ultrasound device comes with a portable stand and easily adjustable viewing angles to make its use remarkably streamlined. In addition, the touchscreen and color capabilities make the product especially helpful in vascular imaging. With built-in DICOM 3.0 and USB options, sharing multiple imaging results between ultrasound, CT, or MRI is effortless.
During these procedures, blood vessels or arteries are mapped for analysis. While Doppler evaluation, CTA, and MRA are necessary imaging methods to chronic wound treatment, fluorescence angiography provides physicians with additional means to measure tissue perfusion. In recent years, this has proved to be an instrumental tactic to providing insight when deciding between minor or major amputation, as well as if limb salvage is viable.
A safe and rapid procedure, fluorescence angiography is useful for vascular surgery, wound care, and limb salvage. For instance, undergoing the procedure 72 hours post-op is a valid means to predicting if provisional surgery following a major amputation is necessary.
Advancements in cameras and displays resulting in clearer imaging, as well as the specialized dye used, has concretized this type of imaging as a staple in vascular treatment. Indocyanine green is a nonradioactive, nontoxic, and water-soluble dye injected into the patient to facilitate the fluorescence angiography procedure. The dye has a half-life between 3 to 5 minutes and is excreted by the liver, making it a biocompatible and safe substance.
Podiatry Today reports that the green dye lays within the “optical window” of the visible and infrared spectrum, ensuring that it fluoresces at the critical location—the blood vessels in deep skin tissue and top layers of fat.
During the imaging procedure, radiologists utilize a fluorescence imaging system to provide clinicians with a real-time tissue perfusion assessment, such as the LUNA Fluorescence Angiography system. Typically, these systems include a near-infrared laser, high-definition camera, a central processing unit, an operator touchscreen, and a patient viewing screen.
Beneficially, LUNA does not require ionizing radiation for imaging, making it a suitable process for populations with kidney function concerns, like diabetics. During the procedure, the green dye is injected into patients immediately before the fluorescence angiography system captures the blood flow exhibited by the now glowing vessels.
Additionally, fluorescence angiography presents an effective approach for targeting lower extremity angiosomes, which can prevent a chronic wound from healing—even with successful revascularization—if not adequately accounted for.
Each angiosome is perfused with specific cutaneous arteries. An angiosome is a network of vessels that penetrate all the tissue layers between skin and bone. While there have been 40 identified angiosomes throughout the human body, six are found in the foot, which are connected to three main arteries. In a study on the effect of revascularization of specific angiosomes for limb salvage, researchers found evidence to support the notion that the treatment leads to increased healing and limb salvage.
In recent years, lower extremity amputation has decreased, leading to improved patient outcome. This has been facilitated through advances in diagnostic imaging that streamlined customized care and targeted treatment. Additionally, shifting the focus on limb salvage via surgical bypass or endovascular intervention before looking to amputation are proven ways to optimize patient outcome. Of all imaging procedures, fluorescence imaging is critical throughout the entire process for its ability to visualize the interior without presenting risk or harm.
